Electrical steel domain investigation with magneto-optical sensor system CMOS-MagView.
First the domains were visualized without any external magnetic field. After some seconds in the video, I used a perment magnet to trigger some domain movements as well as wall motions. These where captured with the CMOS-MagView in realtime (about 6 frames per second).
Feel free to share your comments and thoughts!

In this video, I show how the BlochWall moves. Its Dynamic with the Size and Strength of the field.
The Bloch Wall is VERY EASILY detected.
Senses are Visual and Feel.
Please email me if you have any questions.

published:22 Dec 2014

views:3748

[Keio Spintronics Network - Miyake Laboratory , Osaka University]
Professor Kohno at Osaka University is doing theoretical research on spintronics, from the viewpoint of fundamental physics.
Spintronics uses both the charge and spin of electrons in solids, to achieve electronic devices with new capabilities. Research on spintronics is currently very vigorous worldwide.
Q. "Usually, the aim of spintronics research is to apply it in industry. But I'm studying spintronics theoretically, from the viewpoint of fundamental physics. Specifically, I'm studying phenomena that properties of magnets are manipulated by electric currents, and conversely, dynamical information about magnetization is converted to electrical signals and detected."
The impetus for this research came from an experiment on current-driven domain wall motion.
In that experiment, a magnetic domain wall was moved by a current passing through a wire made of ferromagnetic material. Professor Kohno attempted to explain this experiment theoretically.
Q. "We derived an equation of motion of a domain wall under an applied current. The equation revealed that there are two mechanisms that drives domain walls."
These two mechanisms are spin transfer and momentum transfer. Professor Kohno devised a theory of these mechanisms from the microscopic viewpoint. He also generalized this theory to situations other than domain walls. The equations Professor Kohno obtained led to the idea of driving magnetic vortices by currents, which he suggested to experimenters.
Q. "By attaching leads to a magnetic disk which contains a vortex and passing a current through them, experimenters have succeeded in exciting the vortex core motion, and detecting this motion electrically."
In addition, it's been discovered that, if the current is increased, the orientation of the core can be reversed electrically.
Q. "Next, I calculated theoretically the effects that currents have on general magnetic structures, including domain walls, vortices and all others. The magnetization follows an equation of motion of this form. When there's interaction with the conduction electrons, another term is added to the equation. This is the magnetization, and this is the spin of conduction electrons, and their cross product affects the motion of magnetization. In other words, it acts as a torque. We can derive the effective torques by eliminating conduction electrons. In particular, these alpha and beta terms come from a rather delicate process called spin relaxation, which has to be handled rather precisely. We are constructing a theoretical framework that can treat such effects."
Q. "We're also investigating the inverse effect of spin torque, that is, the effect that magnetization dynamics has on electrons. Suppose a domain wall is driven by, e.g., magnetic field and is in motion. It's been proposed that then an electromotive force is generated. We are also studying this effect theoretically, by including spin relaxation effects, and gauge invariance. This phenomenon itself can be regarded as a mean to convert the information about magnetization dynamics into electrical signals. However, this effect is very small, and detecting it is an experimental challenge. Success has been achieved only recently; In 2008, a group in Texas detected the effect using magnetic domain walls."

published:30 Sep 2010

views:22412

A large number of compass needles are mounted on a Plexiglass sheet. A bar magnet is used to set the needles in motion. When the needles come to a stop, interaction between the needles simulates magnetic domains.

Domain wall

A domain wall is a type of topological soliton that occurs whenever a discrete symmetry is spontaneously broken. Domain walls also sometimes called kinks in analogy with closely related kink solution of the sine-Gordon model. Unstable domain walls can also appear if spontaneously broken discrete symmetry is approximate and there is the metastable vacuum.

A domain (hyper volume) is extended in three spatial dimensions and one time dimension. A domain wall is the boundary between two neighboring domains. Thus a domain wall is extended in two spatial dimensions and one time dimension.

Besides these important cases similar solitons appear in wide spectrum of the models. Here are other examples:

Spontaneous breaking of discrete symmetries at early cosmological epochs can produce domain wall. Formation of domain wall network influence on the late stages of cosmological inflation and the cosmic microwave background radiation. Observations impose severe constraints on the existence of stable domain walls. Those constraints should be accounted for by the models of the beyond Standard Model physics. Unstable cosmic domain walls decay also should produce potentially observable radiation.

Domain (band)

History

1986–1992

Domain first impressed fans of melodic metal back in the 1980s with their first works, "Lost In The City" (still under the old band name Kingdom), "Before The Storm" and "Crack in The Wall", as well as with their hit songs such as 'Lost In The City' and ‚ 'I Don’t Wanna Die'. Single "Heart Of Stone was a title song of german mini-serial "Bastard".

2000–2006

But it was their next albums, "One Million Lightyears From Home" (2001), "The Artefact" (2002) and "The Sixth Dimension" (2003) as well as a successful tour with the rock legends, Glenn Hughes and Joe Lynn Turner (HTP) that secured the quintet a place in the European Melodic Metal scene. With a harder edged sound, Domain still had a good following. And that was when the career of the guitarist Axel "Ironfinger" Ritt (Grave Digger), ex-vocalist Carsten Lizard Schulz (Evidence One et al.), and the long-term band mates keyboarder Erdmann Lange, ex-bass player Jochen Mayer (Boysvoice, Demon Drive, Casanova) and the ex-drummer Stefan Köllner really began…

Magnetic Domain Movement and Wall Motion

Electrical steel domain investigation with magneto-optical sensor system CMOS-MagView.
First the domains were visualized without any external magnetic field. After some seconds in the video, I used a perment magnet to trigger some domain movements as well as wall motions. These where captured with the CMOS-MagView in realtime (about 6 frames per second).
Feel free to share your comments and thoughts!

The Bloch Wall - How the Bloch Wall can Change.

In this video, I show how the BlochWall moves. Its Dynamic with the Size and Strength of the field.
The Bloch Wall is VERY EASILY detected.
Senses are Visual and Feel.
Please email me if you have any questions.

4:49

Fundamental theory of spintronics

Fundamental theory of spintronics

Fundamental theory of spintronics

[Keio Spintronics Network - Miyake Laboratory , Osaka University]
Professor Kohno at Osaka University is doing theoretical research on spintronics, from the viewpoint of fundamental physics.
Spintronics uses both the charge and spin of electrons in solids, to achieve electronic devices with new capabilities. Research on spintronics is currently very vigorous worldwide.
Q. "Usually, the aim of spintronics research is to apply it in industry. But I'm studying spintronics theoretically, from the viewpoint of fundamental physics. Specifically, I'm studying phenomena that properties of magnets are manipulated by electric currents, and conversely, dynamical information about magnetization is converted to electrical signals and detected."
The impetus for this research came from an experiment on current-driven domain wall motion.
In that experiment, a magnetic domain wall was moved by a current passing through a wire made of ferromagnetic material. Professor Kohno attempted to explain this experiment theoretically.
Q. "We derived an equation of motion of a domain wall under an applied current. The equation revealed that there are two mechanisms that drives domain walls."
These two mechanisms are spin transfer and momentum transfer. Professor Kohno devised a theory of these mechanisms from the microscopic viewpoint. He also generalized this theory to situations other than domain walls. The equations Professor Kohno obtained led to the idea of driving magnetic vortices by currents, which he suggested to experimenters.
Q. "By attaching leads to a magnetic disk which contains a vortex and passing a current through them, experimenters have succeeded in exciting the vortex core motion, and detecting this motion electrically."
In addition, it's been discovered that, if the current is increased, the orientation of the core can be reversed electrically.
Q. "Next, I calculated theoretically the effects that currents have on general magnetic structures, including domain walls, vortices and all others. The magnetization follows an equation of motion of this form. When there's interaction with the conduction electrons, another term is added to the equation. This is the magnetization, and this is the spin of conduction electrons, and their cross product affects the motion of magnetization. In other words, it acts as a torque. We can derive the effective torques by eliminating conduction electrons. In particular, these alpha and beta terms come from a rather delicate process called spin relaxation, which has to be handled rather precisely. We are constructing a theoretical framework that can treat such effects."
Q. "We're also investigating the inverse effect of spin torque, that is, the effect that magnetization dynamics has on electrons. Suppose a domain wall is driven by, e.g., magnetic field and is in motion. It's been proposed that then an electromotive force is generated. We are also studying this effect theoretically, by including spin relaxation effects, and gauge invariance. This phenomenon itself can be regarded as a mean to convert the information about magnetization dynamics into electrical signals. However, this effect is very small, and detecting it is an experimental challenge. Success has been achieved only recently; In 2008, a group in Texas detected the effect using magnetic domain walls."

1:55

Simulation of Magnetic Domains

Simulation of Magnetic Domains

Simulation of Magnetic Domains

A large number of compass needles are mounted on a Plexiglass sheet. A bar magnet is used to set the needles in motion. When the needles come to a stop, interaction between the needles simulates magnetic domains.

Magnetic Domain Movement and Wall Motion

Electrical steel domain investigation with magneto-optical sensor system CMOS-MagView.
First the domains were visualized without any external magnetic field. After some seconds in the video, I used a perment magnet to trigger some domain movements as well as wall motions. These where captured with the CMOS-MagView in realtime (about 6 frames per second).
Feel free to share your comments and thoughts!

The Bloch Wall - How the Bloch Wall can Change.

In this video, I show how the BlochWall moves. Its Dynamic with the Size and Strength of the field.
The Bloch Wall is VERY EASILY detected.
Senses are Visual and Feel.
Please email me if you have any questions.

published: 22 Dec 2014

Fundamental theory of spintronics

[Keio Spintronics Network - Miyake Laboratory , Osaka University]
Professor Kohno at Osaka University is doing theoretical research on spintronics, from the viewpoint of fundamental physics.
Spintronics uses both the charge and spin of electrons in solids, to achieve electronic devices with new capabilities. Research on spintronics is currently very vigorous worldwide.
Q. "Usually, the aim of spintronics research is to apply it in industry. But I'm studying spintronics theoretically, from the viewpoint of fundamental physics. Specifically, I'm studying phenomena that properties of magnets are manipulated by electric currents, and conversely, dynamical information about magnetization is converted to electrical signals and detected."
The impetus for this research came from an e...

published: 30 Sep 2010

Simulation of Magnetic Domains

A large number of compass needles are mounted on a Plexiglass sheet. A bar magnet is used to set the needles in motion. When the needles come to a stop, interaction between the needles simulates magnetic domains.

Magnetic Domain Movement and Wall Motion

Electrical steel domain investigation with magneto-optical sensor system CMOS-MagView.
First the domains were visualized without any external magnetic field. Af...

Electrical steel domain investigation with magneto-optical sensor system CMOS-MagView.
First the domains were visualized without any external magnetic field. After some seconds in the video, I used a perment magnet to trigger some domain movements as well as wall motions. These where captured with the CMOS-MagView in realtime (about 6 frames per second).
Feel free to share your comments and thoughts!

Electrical steel domain investigation with magneto-optical sensor system CMOS-MagView.
First the domains were visualized without any external magnetic field. After some seconds in the video, I used a perment magnet to trigger some domain movements as well as wall motions. These where captured with the CMOS-MagView in realtime (about 6 frames per second).
Feel free to share your comments and thoughts!

The Bloch Wall - How the Bloch Wall can Change.

In this video, I show how the BlochWall moves. Its Dynamic with the Size and Strength of the field.
The Bloch Wall is VERY EASILY detected.
Senses are Visu...

In this video, I show how the BlochWall moves. Its Dynamic with the Size and Strength of the field.
The Bloch Wall is VERY EASILY detected.
Senses are Visual and Feel.
Please email me if you have any questions.

In this video, I show how the BlochWall moves. Its Dynamic with the Size and Strength of the field.
The Bloch Wall is VERY EASILY detected.
Senses are Visual and Feel.
Please email me if you have any questions.

[Keio Spintronics Network - Miyake Laboratory , Osaka University]
Professor Kohno at Osaka University is doing theoretical research on spintronics, from the viewpoint of fundamental physics.
Spintronics uses both the charge and spin of electrons in solids, to achieve electronic devices with new capabilities. Research on spintronics is currently very vigorous worldwide.
Q. "Usually, the aim of spintronics research is to apply it in industry. But I'm studying spintronics theoretically, from the viewpoint of fundamental physics. Specifically, I'm studying phenomena that properties of magnets are manipulated by electric currents, and conversely, dynamical information about magnetization is converted to electrical signals and detected."
The impetus for this research came from an experiment on current-driven domain wall motion.
In that experiment, a magnetic domain wall was moved by a current passing through a wire made of ferromagnetic material. Professor Kohno attempted to explain this experiment theoretically.
Q. "We derived an equation of motion of a domain wall under an applied current. The equation revealed that there are two mechanisms that drives domain walls."
These two mechanisms are spin transfer and momentum transfer. Professor Kohno devised a theory of these mechanisms from the microscopic viewpoint. He also generalized this theory to situations other than domain walls. The equations Professor Kohno obtained led to the idea of driving magnetic vortices by currents, which he suggested to experimenters.
Q. "By attaching leads to a magnetic disk which contains a vortex and passing a current through them, experimenters have succeeded in exciting the vortex core motion, and detecting this motion electrically."
In addition, it's been discovered that, if the current is increased, the orientation of the core can be reversed electrically.
Q. "Next, I calculated theoretically the effects that currents have on general magnetic structures, including domain walls, vortices and all others. The magnetization follows an equation of motion of this form. When there's interaction with the conduction electrons, another term is added to the equation. This is the magnetization, and this is the spin of conduction electrons, and their cross product affects the motion of magnetization. In other words, it acts as a torque. We can derive the effective torques by eliminating conduction electrons. In particular, these alpha and beta terms come from a rather delicate process called spin relaxation, which has to be handled rather precisely. We are constructing a theoretical framework that can treat such effects."
Q. "We're also investigating the inverse effect of spin torque, that is, the effect that magnetization dynamics has on electrons. Suppose a domain wall is driven by, e.g., magnetic field and is in motion. It's been proposed that then an electromotive force is generated. We are also studying this effect theoretically, by including spin relaxation effects, and gauge invariance. This phenomenon itself can be regarded as a mean to convert the information about magnetization dynamics into electrical signals. However, this effect is very small, and detecting it is an experimental challenge. Success has been achieved only recently; In 2008, a group in Texas detected the effect using magnetic domain walls."

[Keio Spintronics Network - Miyake Laboratory , Osaka University]
Professor Kohno at Osaka University is doing theoretical research on spintronics, from the viewpoint of fundamental physics.
Spintronics uses both the charge and spin of electrons in solids, to achieve electronic devices with new capabilities. Research on spintronics is currently very vigorous worldwide.
Q. "Usually, the aim of spintronics research is to apply it in industry. But I'm studying spintronics theoretically, from the viewpoint of fundamental physics. Specifically, I'm studying phenomena that properties of magnets are manipulated by electric currents, and conversely, dynamical information about magnetization is converted to electrical signals and detected."
The impetus for this research came from an experiment on current-driven domain wall motion.
In that experiment, a magnetic domain wall was moved by a current passing through a wire made of ferromagnetic material. Professor Kohno attempted to explain this experiment theoretically.
Q. "We derived an equation of motion of a domain wall under an applied current. The equation revealed that there are two mechanisms that drives domain walls."
These two mechanisms are spin transfer and momentum transfer. Professor Kohno devised a theory of these mechanisms from the microscopic viewpoint. He also generalized this theory to situations other than domain walls. The equations Professor Kohno obtained led to the idea of driving magnetic vortices by currents, which he suggested to experimenters.
Q. "By attaching leads to a magnetic disk which contains a vortex and passing a current through them, experimenters have succeeded in exciting the vortex core motion, and detecting this motion electrically."
In addition, it's been discovered that, if the current is increased, the orientation of the core can be reversed electrically.
Q. "Next, I calculated theoretically the effects that currents have on general magnetic structures, including domain walls, vortices and all others. The magnetization follows an equation of motion of this form. When there's interaction with the conduction electrons, another term is added to the equation. This is the magnetization, and this is the spin of conduction electrons, and their cross product affects the motion of magnetization. In other words, it acts as a torque. We can derive the effective torques by eliminating conduction electrons. In particular, these alpha and beta terms come from a rather delicate process called spin relaxation, which has to be handled rather precisely. We are constructing a theoretical framework that can treat such effects."
Q. "We're also investigating the inverse effect of spin torque, that is, the effect that magnetization dynamics has on electrons. Suppose a domain wall is driven by, e.g., magnetic field and is in motion. It's been proposed that then an electromotive force is generated. We are also studying this effect theoretically, by including spin relaxation effects, and gauge invariance. This phenomenon itself can be regarded as a mean to convert the information about magnetization dynamics into electrical signals. However, this effect is very small, and detecting it is an experimental challenge. Success has been achieved only recently; In 2008, a group in Texas detected the effect using magnetic domain walls."

Simulation of Magnetic Domains

A large number of compass needles are mounted on a Plexiglass sheet. A bar magnet is used to set the needles in motion. When the needles come to a stop, interac...

A large number of compass needles are mounted on a Plexiglass sheet. A bar magnet is used to set the needles in motion. When the needles come to a stop, interaction between the needles simulates magnetic domains.

A large number of compass needles are mounted on a Plexiglass sheet. A bar magnet is used to set the needles in motion. When the needles come to a stop, interaction between the needles simulates magnetic domains.

Magnetic Domain Movement and Wall Motion

Electrical steel domain investigation with magneto-optical sensor system CMOS-MagView.
First the domains were visualized without any external magnetic field. After some seconds in the video, I used a perment magnet to trigger some domain movements as well as wall motions. These where captured with the CMOS-MagView in realtime (about 6 frames per second).
Feel free to share your comments and thoughts!

The Bloch Wall - How the Bloch Wall can Change.

In this video, I show how the BlochWall moves. Its Dynamic with the Size and Strength of the field.
The Bloch Wall is VERY EASILY detected.
Senses are Visual and Feel.
Please email me if you have any questions.

Fundamental theory of spintronics

[Keio Spintronics Network - Miyake Laboratory , Osaka University]
Professor Kohno at Osaka University is doing theoretical research on spintronics, from the viewpoint of fundamental physics.
Spintronics uses both the charge and spin of electrons in solids, to achieve electronic devices with new capabilities. Research on spintronics is currently very vigorous worldwide.
Q. "Usually, the aim of spintronics research is to apply it in industry. But I'm studying spintronics theoretically, from the viewpoint of fundamental physics. Specifically, I'm studying phenomena that properties of magnets are manipulated by electric currents, and conversely, dynamical information about magnetization is converted to electrical signals and detected."
The impetus for this research came from an experiment on current-driven domain wall motion.
In that experiment, a magnetic domain wall was moved by a current passing through a wire made of ferromagnetic material. Professor Kohno attempted to explain this experiment theoretically.
Q. "We derived an equation of motion of a domain wall under an applied current. The equation revealed that there are two mechanisms that drives domain walls."
These two mechanisms are spin transfer and momentum transfer. Professor Kohno devised a theory of these mechanisms from the microscopic viewpoint. He also generalized this theory to situations other than domain walls. The equations Professor Kohno obtained led to the idea of driving magnetic vortices by currents, which he suggested to experimenters.
Q. "By attaching leads to a magnetic disk which contains a vortex and passing a current through them, experimenters have succeeded in exciting the vortex core motion, and detecting this motion electrically."
In addition, it's been discovered that, if the current is increased, the orientation of the core can be reversed electrically.
Q. "Next, I calculated theoretically the effects that currents have on general magnetic structures, including domain walls, vortices and all others. The magnetization follows an equation of motion of this form. When there's interaction with the conduction electrons, another term is added to the equation. This is the magnetization, and this is the spin of conduction electrons, and their cross product affects the motion of magnetization. In other words, it acts as a torque. We can derive the effective torques by eliminating conduction electrons. In particular, these alpha and beta terms come from a rather delicate process called spin relaxation, which has to be handled rather precisely. We are constructing a theoretical framework that can treat such effects."
Q. "We're also investigating the inverse effect of spin torque, that is, the effect that magnetization dynamics has on electrons. Suppose a domain wall is driven by, e.g., magnetic field and is in motion. It's been proposed that then an electromotive force is generated. We are also studying this effect theoretically, by including spin relaxation effects, and gauge invariance. This phenomenon itself can be regarded as a mean to convert the information about magnetization dynamics into electrical signals. However, this effect is very small, and detecting it is an experimental challenge. Success has been achieved only recently; In 2008, a group in Texas detected the effect using magnetic domain walls."

Simulation of Magnetic Domains

A large number of compass needles are mounted on a Plexiglass sheet. A bar magnet is used to set the needles in motion. When the needles come to a stop, interaction between the needles simulates magnetic domains.